The present invention relates to a method for making organooxysilanes. More particularly, the present invention relates to a process involving the reaction of a tetraorganooxysilane in the presence of a metal hydride.
Organooxysilanes are silicon-containing compounds of the formula R.sub.m Si(RO).sub.n where each R independently represents a monovalent hydrocarbon group such as an alkyl group, aryl group, aralkyl groups, alkaryl groups, cycloalkyl groups, or bicycloalkyl groups; "n" is in a range between 1 and 3; "m" is in a range between 1 and 3; and "n+m" is 4. Silicon-containing compounds with silicon-carbon bonds, such as organooxysilanes, are commonly made from silicon dioixide via elemental silicon. Unfortunately, elemental silicon is manufactured from silicon dioxide by an energy intrusive reduction process.
The process commonly used commercially for the production of silicones and more particularly, alkoxysilanes, was first described by Rochow et al., U.S. Pat. No. 2,473,260. The Rochow process uses silicon, also referred to as elemental silicon, as a starting material. To prepare elemental silicon, silicon dioxide must be reduced. The elemental silicon is then oxidized to yield alkoxysilanes via a reaction of the silicon with methanol in the presence of a copper catalyst. It is well known in the art that the silicon-oxygen bond in silicon dioxide is extremely stable. In order to break the silicon-oxygen bond, a large amount of energy is consumed when silicon dioxide is reduced to elemental silicon. Thus, due to the large amount of energy needed to break the silicon-oxygen bond, the synthesis of silicones from silicon dioxide using the Rochow process is expensive and not energy efficient.
In the past, the synthesis of silicon-containing compounds with silicon-carbon bonds has relied heavily on the reduction of silicon dioxide to elemental silicon. Unfortunately, the large amount of energy needed for synthesizing silicones such as organooxysilanes from silicon dioxide can be problematic. Thus, new synthetic routes are constantly being sought which can form silicon-carbon bonds.